1. Field of the Invention
This invention relates broadly to Moineau devices in which a helical profiled rotor acts in conjunction with a helical profiled stator as a motor or a pump, and more specifically to the use of polymer materials for such Moineau devices.
2. Related Art
Moineau devices (sometimes referred to as progressive cavity devices) typically include a power section that includes a rotor with a profiled helical outer surface disposed within a stator with a profiled helical inner surface. The helical outer surface of the rotor sealably engages the helical inner surface of the stator to create cavities which progress axially as the rotor is rotated relative to the stator. In a Moineau pump, relative rotation is provided between the stator and the rotor which causes fluids (and possibly solids suspended therein) to be passed through the cavities of the device. In a Moineau motor, a fluid source is provided to the cavities of the device which causes the cavities to progress and induce relative motion between the stator and the rotor. Moineau pumps and motors have many uses. For example, a Moineau motor is often used in hydrocarbon extraction applications for drilling a subterranean well bore by applying drilling mud under pressure to the cavities of the motor, which induces relative motion between the stator and the rotor that is used to power a drill bit for drilling the well bore.
Conventional Moineau devices employ a steel rotor and an elastomeric material bonded to steel for the stator. The elastomeric material of the stator can be natural rubber, G.R.S., Neoprene, Butyl and Nitrile rubbers, soft PVC, fluoroelastomers, etc. The elastomeric material of the stator is required to be soft enough to maintain the sealed cavity, yet be hard enough to withstand the abrasive wear from the working contact between the rotor and the stator.